45(5 
ON THE PRODUCTION OF HAIR ON THE 
the attention of observers. In addition to this, embryotomy has 
shewn that the skin and the mucous membranes are the parts 
that are first formed ; while chemistry has demonstrated the com- 
plete identity of the mucus and the epithelium with which 
the internal teguments are lined, and the epidermic productions, 
hairy or horny, of which the skin is composed. 
To all these points of analogy, and to some others of less 
importance that may be observed in these membranes in a state 
of health, pathological anatomy has added resemblances in the 
changes, the degeneracies, and the transformations which they 
undergo ; while physiology has demonstrated the strict relation 
there is between many of the functions common to them both, 
and how numerous are the sympathies which unite them in 
a state of health as well as of disease. 
Notwithstanding, however, this apparent identity of the skin 
and the mucous membrane in many particulars, we cannot fail of 
recognizing evident differences of anatomical structure. It will 
be only necessary for me to mention one, to which I am 
desirous of directing the particular attention of the reader — the 
production of hair seems to be peculiar to the skin, and it ceases 
to be remarked as soon as the mucous membrane commences. 
It is true, that some facts, and which have been considered as 
anomalies, have shewn that these productions may accidentally 
exist on certain parts of internal teguments, both in man and 
some of the inferior animals. 
In man several cases of this kind have been observed. Bichet, 
in his “ Anatomie Generate” (tom. iv, p. 534) says that hairs 
are sometimes formed on the mucous membrane of various parts, 
and that he has seen it in the bladder, the stomach, and the 
intestines. Beclard and many other anatomists have said that 
they have found it on different parts of the mucous membrane 
in the human being. It has been particularly remarked on the 
conjunctiva of different animals. La Recueil de Med. Vet. 
(1824, p. 84 and 229) contains many facts of this kind, pub- 
lished by different veterinarians, and from which it appears that 
hair has been observed on the conjunctiva and cornea lucida 
of different animals, such as the horse, the ass, and the dog # . 
However, I had not known of any case in which these pro- 
ductions had been met with on the membrane of the digestive 
passages of quadrupeds, although the existence of hard sub- 
* A tuft of hair, consisting of at least thirty fibres, and nearly two inches 
in length, was congenital on the centre of the cornea of an Abyssinian lamb in 
the menagerie of the Zoological Society of London. It was a great nuisance 
to the little animal, which never throve, and died at about three months old. 
I would have plucked the hair away, but that it was a kind of natural 
curiosity. — Y. 
